<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
    <input type="text" v-model="num1">
    <input type="text" v-model="num2">
    <input type="button" value="加" @click="f(1)">
    <input type="button" value="减" @click="f(2)">
    <input type="button" value="乘" @click="f(3)">
    <input type="button" value="除" @click="f(4)">
    <div>{{result}}</div>
</div>

<script src="https://cdn.staticfile.org/vue/2.2.2/vue.min.js"></script>
<script>
  let v = new Vue({
    el:"body>div",
    data:{
        num1:"",
        num2:"",
        result:""
    },
    methods:{
      f(x) {
      /*if (isNaN(i1.value) || isNaN(i2.value)){
          v.result = "输入有误！！"
          return;
      }*/
      switch (x) {
          case 1:
              v.result = (v.num1*1+v.num2*1)
              break
          case 2:
              v.result = (v.num1-v.num2)
              break
          case 3:
              v.result = (v.num1*v.num2)
              break
          case 4:
              v.result = (v.num1/v.num2)
              break
      }
  }
    }

  })
</script>
</body>
</html>